Billiard cue

ABSTRACT

Disclosed is a billiard cue that realizes weight reduction of a top end portion of a shaft without reducing structural strength, that improves stability and controllability in hitting a ball, and that gives a player a comfortable feeling hit and fulfilling sensation of billiard play. This billiard cue is a single rod-shape body including a butt and a shaft connected to each other through a joint. The shaft is provided with a hollow section running inside of the shaft along the center axis in the longitudinal direction, and an internal support structure is arranged within the hollow section to support the hollow section from inside.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a billiard cue, and particularly to a billiard cue having a structure where a butt and a shaft are connected to each other through a shaft and formed as a single rod-like body.

2. Description of the Related Art

Billiard cues that are widely used today are usually constructed by a shaft and a butt which is attached to the back end of the shaft, and the shaft and the butt are connected to each other and formed into a single rod-like body. As for a shaft of a billiard cue, it is critical to adjust its weight, hardness, and compression characteristics for absorbing hitting force so that they all have desired values.

Also, this kind of billiard cue as a whole is required to have appropriate hardness for accurate shots by giving some flexibility to the top end side of a shaft which hits a ball and by giving hardness to the back end side of the shaft which is connected to a butt.

There is known a structure of such billiard cue, where a bore (a cut-out hole) is made on the top end side of the shaft to reduce its weight and also to provide flexibility to the top end side of the shaft. For example, this structure is disclosed in Japanese translation of PCT/US1995/012666 (tokuhyou-hei 11-502428) and the like.

A conventional billiard cue having a bore (hollow portion) in the top end side of the shaft contributes a weight reduction of the top end portion and thus realizes quick acceleration and outward deflection. However, since the top end side of the shaft is hollow and coreless, a player is unable to experience a subtle feeling of ball hitting easily. Moreover, since the structure of such billiard cue is that a hole or a hollow is provided inside, the billiard cue is susceptible to vertical and horizontal impacts and easy to break.

SUMMARY OF THE INVENTION

An object of the invention is to provide a billiard cue that solve the above problems, that enables a player to experience different feelings of hitting a ball easily, that is easy to control a ball, that can improve a sensation from sound and a subtle feeling conveyed to a player's hand, that is structurally durable to impacts and difficult to break, that is easy to reduce weight of the top end portion of a shaft, and that gives a player a comfortable feeling hit and fulfilling sensation of billiard play.

In order to solve the above-described problems, the following means is to be employed:

(1) In a billiard cue formed into a single rod-like body by a butt and a shaft that are connected to each other through a joint,

the shaft is provided with a hollow section running through inside of the shaft along a center axis in a longitudinal direction, and

an internal support structure is provided within the hollow section to support the hollow section from inside.

(2) In the billiard cue according to (1),

the internal support structure in the hollow section is either a structure (a) including an outer frame body which abuts on an inner wall surface of the hollow section to support the hollow section and a support member which supports the outer frame body, or a structure (b) including a support member which abuts on the inner wall surface of the hollow section and supports the hollow section, or a structure having both of (a) and (b).

Here, the internal support structure may be provided in the entire hollow section or only in a predetermined (certain) part of the hollow section.

Further, in the hollow section, there maybe an empty space where the internal support structure is not provided, or a space where only the outer frame body of the internal support structure is provided but inside of the internal support structure remains empty. Other material (substance) may fill in or be placed in these spaces, or the spaces may be left empty.

(3) In the billiard cue according to (1) or (2), the shaft is a single rod-like body made by combining a shaft body, a ferrule section, and a top end member in this order, and the hollow section is provided through inside of the shaft body and the ferrule section.

Here, the shaft is provided with the shaft body and the ferrule section. The shaft body is a rod-like body having a first body end portion to which the butt is connected and the second body end portion on the other side. The ferrule section is attached to the second body end or the second body end side of the shaft body. The hollow section is provided so that it runs through inside of the ferrule section to the inside of the shaft body. The ferrule section has a cylindrical shape with or without a bottom, and the top end member is attached to the ferrule section or the internal support structure directly or through other member. Note that member imposed between the top end member and the ferrule section or the internal support structure may be an elastic member or the second ferrule member.

(4) In the billiard cue according to (1) or (2), the shaft is a single rod-like body made by combining a shaft body in which the hollow section is provided, an extended connecting section, and a top end member in this order, and the internal support structure is a single-piece structure where a support member within the hollow section and the extended connecting section are formed into a single piece.

Here, the shaft body has the first body end portion to which the butt is connected and the second body end portion on the other side. The extended connecting section is a top end section of the internal support structure, provided on the second body end portion side of the shaft body. Also, the extended connecting section is an extension of the shaft body and has a rod-like shape with the same external appearance as the shaft body, and the outer circumference surface of the extended connecting section is exposed. Further, the top end member is attached to the internal support structure directly or through other member. This member placed between the top end member and the internal support structure may be an elastic member or a ferrule member.

(5) In the billiard cue according to any one of (1) to (4)

a material of the internal support structure is any of light-weight wood, urethane foam, expanded polystyrene, expanded polyethylene, Styrofoam, a plastic material, a fiber material, and a light-weight metal material.

The following outstanding effects are obtained from the billiard cue of the present invention.

According to the present invention, a hollow section is provided within a shaft or the top end side of the shaft along the center axis of the shaft, and an internal support structure is placed within the hollow section to support the hollow section from inside. Therefore, the internal support structure in the hollow section of the shaft realizes a construction of the shaft that is very similar to a shaft having a solid body with a core.

According to the present invention, it becomes easy to control a ball and improve a subtle feeling conveyed to player's hand.

According to the present invention, strength of the entire stick of a billiard cue is improved. Particularly, strength of the top end of a shaft is remarkably improved compared to a conventional pipe-type shaft and durability to breakage and damages is also greatly improved compared to a conventional one.

According to the present invention, sizes, dimensions, positions, materials of the hollow section and the internal support structure within a billiard cue can be arbitrarily decided. Therefore, in aiming at weight reduction of the top end side of a shaft, there is a lot of flexibility when designing the hollow section and the internal support structure to suit players' preferences.

By employing a structure where other member such as an elastic material is placed between the ferrule section and the tip section of the shaft, the absorption of impact of a ball is improved and ball contact duration is extended. Thus, a player's feeling of billiard play is improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a structure view of the entire billiard cue according to an embodiment of the present invention;

FIGS. 2-1(1) to 2-1(2) are structure views of a shaft of a billiard cue according to the embodiment of the present invention;

FIG. 2-2(3 a) to 2-2(5) are views of a billiard cue according to the embodiment of the present invention, showing the structures of a shaft in cross section and external appearances of an internal support structure;

FIGS. 3(1) to 3(3) are views showing a structure and a manufacturing method of a shaft of a billiard cue according to the embodiment of the present invention.

FIGS. 4(1) and 4(2) are views of a billiard cue according to the embodiment of the present invention, depicting a structure and a manufacturing method of a shaft having an internal support structure in which an extended connecting section and a hollow section are formed into a single-piece structure without a ferrule section;

FIGS. 5(A) to 5(H) are enlarged cross-sectional views illustrating example structures of the top end side of a shaft of a billiard cue according to the embodiment of the present invention;

FIG. 6 is a view showing an example of an internal structure of a shaft of a billiard cue according to another embodiment of the present invention; and

FIGS. 7(1) to 7(3) are views illustrating examples of an internal structure of a shaft of a billiard cue according to yet another embodiment of the present invention, and FIGS. 7(1) and 7(2) depict a structure where balsa wood is inserted within the shaft on the top end side thereof, and FIG. 7(3) depicts a combined structure of balsa wood and foamed material.

DETAILED DESCRIPTION OF THE INVENTION

Next, embodiments of a billiard cue according to the present invention are detailed with reference to the attached drawings.

FIG. 1 is a view showing the overall structure of a billiard cue 300 according to an embodiment of the present invention, FIGS. 2-1(1) to 2-2(5) are views illustrating examples of the internal structure of a shaft of a billiard cue, FIGS. 3(1) to 3(3) are explanatory views of example structures and a manufacturing method of a shaft of a billiard cue, FIGS. 4(1) and 4(2) are explanatory views of an example of an internal support structure having a single-piece construction including an extended connecting section and a support body of a hollow section without the use of a ferrule section, FIGS. 5(A) to 5(H) are enlarged cross-sectional views showing example structures of the top end side of a shaft, and FIG. 6 is a structural view showing an example of an internal structure of a shaft of a billiard cue according to another embodiment of the present invention.

FIG. 1 is a view showing a billiard cue 300 according to an embodiment of the present invention. The billiard cue 300 includes two major members: a shaft 100 for hitting a ball (not shown); and a butt 200 attached to the back end side of the shaft 100 and gripped by a user. The shaft 100 and the butt 200 are connected to each other with joints (J1 and J2), forming a single bar-like structure. Usually, the shaft 100 and the butt 200 are made from iron wood such as maple, but other materials including metal such as aluminum, synthetic resin, glass fiber, graphite, carbon fiber may also be used.

The shaft 100 has a first body end portion 10 a on the side to which the butt 200 is connected, and a second body end portion 10 b on the other side. The shaft 100 has an integrated bar-like construction including a rod-shaped shaft body 10, a ferrule section 40 having a shape that matches the second body end portion 10 b and attached to the shaft body 10, and a tip section (an end member) 50 attached to the end portion of the ferule section 40. The ferrule section 40 is made from various materials including nylon, ABS resin, urethane resin, synthetic resin and the like. The tip section 50 for hitting a ball is made from various materials including pigskin, cow skin, fiber resin and the like. The materials for the ferrule'section and the tip section can be selected as appropriate to suit player's preferences.

In the shaft 100, there is a hollow section 20 running through inside of the shaft along its axis in the longitudinal direction between the end portion 20 a of the ferrule section 40 and a predetermined position 20 b of the shaft body 10. Within the hollow section 20 is an internal support structure 30 which supports the hollow section 20 from inside.

Providing the hollow section 20 within the shaft 100 contributes to weight reduction. In addition, as for the internal support structure 30 accommodated in the hollow section 20, use of a skeletal body made by combining a number of members instead of use of a solid body contributes to weight saving as it leaves a lot of unfilled spaces. Moreover, by using a material lighter than that of the shaft body 10 (iron wood such as maple) for the internal support structure 30, its weight is reduced even further.

In the shaft 100 illustrated in FIG. 1, each member is formed so that the shaft body 10 and the ferrule section 40 are joined via their matching cross-sections and the ferrule section 40 and the tip section 50 are also joined together via their matching cross-sections, without producing any uneven outer surface. Therefore, the entire structure of the shaft is formed into an integrated bar shape. The shaft body 10 and the ferrule potion 40 are joined together by abutting their matching cross sections on each other, or by surface-to-surface attachment of the matching cross section. The ferrule section 40 and the tip section 50 are joined together likewise.

FIGS. 2-1 to 2-2 show examples of the internal structure of the shaft of a billiard cue. FIG. 2-1(1) is a structural view of a cross section of a shaft 110 in the longitudinal direction, FIG. 2-1(2.) is an enlarged cross-sectional structural view of the top end side of the shaft 110 in the longitudinal direction, FIGS. 2-2(3 a) to 2-2(3 e) are structural views of an internal support structure located in the hollow section within the shaft in cross section at right angle relative to the longitudinal direction, FIG. 2-2(4) is an external perspective view of a construction of the structure (3 c), and FIG. 2-2(5) is an external perspective view of another example of the structure (3 c).

In FIG. 2-1(1), the shaft 110 has a joint J3 on the side where a butt (not shown) is connected and a ferrule section 41 on the other side. Further, a tip section 51 is attached to the end of the ferrule section 41, so the entire shaft 110 has an externally-tapered rod shape or narrow cylindrical shape. To obtain this shaft 110, a shaft body 11, the ferrule section 41 and the tip section 51 are connected together in this order into a single piece without any visible uneven surface and joint line.

The ferrule section 41 of the shaft 110 has a cylindrical shape with a bottom in a U-shape in cross section. Between the bottom portion 31 a and a predetermine position 31 b of the shaft body 11, a hollow section 21 is provided within the shaft along the core axis of the shaft in the longitudinal direction. Also, an internal support structure 31 is placed within the hollow section 21, being in contact with the inner wall of the hollow section 21. The internal support structure 31 is constructed to support the hollow section 21 from within the shaft.

The above internal support structure 31 is designed to have its outer frame member that matches the inner wall shape of the hollow section 21 and supports the hollow section 21 by being abutted on or in contact with the inner wall. The length h in longitudinal direction between the end portion 41 a of the ferrule section 41 and the internal support structure 31 is a value that can be decided as appropriate so that the weight and balance of the top end portion of a billiard cue is adjusted to suit user's preferences. For example, as for a standard shaft manufactured by maple wood, a preferred length h including the hollow section 21 is between 18 and 20 cm and, more preferably, about 20 cm.

Similarly, the shaft 110 shown in FIG. 2-1(2) which shows an enlarged view of the top end side of the shaft 110 shown in FIG. 2-1(1) includes the shaft body 11, the ferrule section 41, and the tip section 51 at the end of the ferrule section 41, and the hollow section 21 is provided within the shaft 110. Also, the internal support structure 31 is positioned within the hollow section 21. The internal support structure 31 is provided with a structural member that is in close contact with the inner wall of the hollow section 21. The left end portion 31 b of the inner support structure 31 abuts on the inner wall of the hollow section 21 and the right end portion 31 a of the same abuts on the bottom portion 41 b of the ferrule section 41.

Further, in FIGS. 2-1(1) to 2-1(2), the longitudinal length of the hollow section 21 and the length of the internal support structure 31 are equal, and thus there is no space on both sides of the hollow section 21. However, the length of the internal support structure 31 may be reduced to create some spaces in the hollow section 21.

Further, where there are spaces within or on the both sides of the internal support structure 31, these spaces maybe filled with a material such as a plastic material, an expanded polystyrene material, carbon fiber, glass fiber and the like and construct a solid layer.

Next, the construction of the internal support structure is described with reference to the cross sections of the shaft at right angle relative to the longitudinal direction, shown. in FIGS. 2-2(3 a) to 2-2(3 e).

The structures shown in FIG. 2-2 (3 a) has a hollow section 23 inside an outer layer portion ga of the shaft body or the ferrule section, and an outer frame body a1 and a number of support bodies a2 as the internal support structure. The outer frame body a1 is in close contact with the inner wall of the hollow section 23 and supports the hollow section 23, and the support bodies a2 hold the structure of the outer frame a1. The outer frame body a1 is shaped so that it abuts on and supports the inner wall of the hollow section 23. Therefore, since the inner wall of the hollow section 23 has a cylindrical shape, the outer frame body a1 also has a cylindrical shape and is circular in cross section. However, the outer frame a1 does not always need to have a perfect cylindrical shape and can be any shape as long as it can evenly support the structure of the cylindrical hollow section 23. For example, the outer frame al may be made of a combination of many skeletal members or rod members providing a lot of spaces or hollows in-between the members (see FIG. 2-2 (5)). In this structure (3 a), many support bodies a2 for supporting the outer frame body a1 from inside form a group of many equilateral hexagons in cross section, and the blank areas between the structural members represent spaces or hollows. This can be regarded as a “honey comb” structure.

Since the structure (3 a) is depicted in cross section, the structure of the internal support structure may be constructed by combining long plate-like members in the longitudinal direction so that the structure has the same pattern in each cross section (see FIG. 2-2(4)). Alternatively, instead of having the same cross section at the right angle in the longitudinal direction, a lot of skeletal members or rod members may be combined so that only some cross sections have the pattern of the structure (3 a) with a lot of spaces and hollows (see FIG. 2-2(5)).

The structure (3 b) has a hollow section 24 within an outer layer portion gb of a shaft or a ferrule portion. The internal support structure is provided with an outer frame body b1 which is in close contact with the inner wall of the hollow section 24 and supports the hollow section 24, and five support bodies b2 which support the structure of the outer frame body b1. Like the structure (3 a), the outer frame body b1 is in contact with the hollow section 24 and has a circular ring shape in cross section. The five support bodies b2 which support the structure of the outer frame b1 are arranged in a radial pattern at equal angle towards the inner wall surrounding them. These support bodies b2 may have a plate shape extending in the longitudinal direction or may be formed by a number of rod-shaped members extending from the center to the surrounding inner wall. This structure (3 b) can be referred to as a “lotus leaf” structure from its cross sectional pattern.

The structure shown in FIG. 2-2 (3 c) has a hollow section 25 inside an outer layer portion gc of a shaft body or a ferrule section. An outer frame body c1 and three support bodies c2 are provided as an internal support structure. The outer frame body cl abuts on the inner wall surface of the hollow section 25 and supports the hollow section 25, and the support bodies c2 hold the structure of the outer frame c1. This structure (3 c) has the same construction as the structure (3 b) except that this structure has a fewer support bodies and thus can be called the same “lotus leaf” structure.

FIG. 2-2(4) is an external perspective view of the internal support structure (3 c). This structure includes the cylindrical outer frame body cl and the three support bodies c2 having a rectangular plate shape, extending in the longitudinal direction and also arranged in a radial pattern from the center to the surrounding inner wall at an equal angle. FIG. 2-2(5) is an external perspective view showing another example of the internal support structure (3 c). This structure is made by combining a number of rod-shaped members or circular members including frame body members x1, internal support members y1 and support members between the frame bodies z1.

The structure shown in FIG. 2-2(3 d) has a hollow section 26 within an outer layer portion gd of a shaft body or a ferrule section. This structure is provided with a circular outer frame body d1 which is in contact with the hollow section like the structures (3 a) to (3 c), and five support bodies d1 to d5 as an internal support structure. These five support bodies d1 to d5 extend from an inner frame body d6 in a radial pattern towards the surrounding outer frame body d1 at an equal angle. The inner frame body d6 has a circular shape and is approximately co-centric with the outer frame body d1. These support bodies d1 to d5 may be configured by plate-shape members extending in the longitudinal direction or a number of rod-shaped members extending from the center to the surrounding inner wall. This structure (3 d) may be referred to as an “automotive wheel type” or “sword guard type” structure from its cross-sectional pattern.

The structure shown in FIG. 2-2 (3 e) has a hollow section 27 within an outer layer portion ge of a shaft body or a ferrule section. Unlike the structures (3 a) to (3 d), this structure is not provided with an outer frame body (a1 to d1) which is in contact with the hollow section, but has eight support bodies e1 to e8 as an internal support structure. The outer ends of these support bodies e1 to e8 come into contact with the inner wall of the hollow section 27, supporting the structure of the hollow section 27. The support bodies e1 to e8 extend in a radial pattern from the center of the hollow section 27 towards the surrounding inner wall at an equal angle. The support bodies e1 to e8 may be a plate-shaped bodies extending in the longitudinal direction, but may also be formed by a number of skeletal rod-shaped bodies extending from the center to the surrounding inner wall. This structure (3 e) may be called a “rib-type” structure from its cross-sectional pattern.

FIGS. 3(1) to 3(3) are explanatory views showing an example of a structure and a manufacturing method of an internal support structure of a shaft of a billiard cue according to the present invention.

The shaft illustrated in FIG. 3(1) includes a cylindrical shaft body 13, a ferrule section 43 that is contiguous with the shaft body 13, a tip portion 53 and an internal support structure 33. A hollow section 27 a is provided within the shaft body 13 and is open on the side of the ferrule section 43, and a hollow section 27 b is provided within the ferrule 43 and is open on the side of the shaft body 13. These hollow sections 27 a and 27 b are formed into a single cylindrical space, and the internal support structure 33 is located within this space.

The internal support structure 33 shown in FIG. 3(1) has a cylindrical outer shape which fits the inner wall of the hollow section 13, and has the structure shown in FIG. 2-2(3 b). This internal support structure 33 includes an outer frame body e1 which is in close contact with the inner wall surface of the hollow section 13 and supports the same, and five support bodies e2 holding the structure of the outer frame e1 from inside. The blank areas between the outer frame body e1 and the support bodies e2 are spaces S3 (black areas).

The shaft body 13 is manufactured from wood such as maple, glass fiber, carbon fiber, light metal or the like. The column-like hollow section 27 inside the shaft body 13 can be designed so that it is coaxial with the shaft body 13 and the ferrule section 43, and that the outer diameter and length of the column shape of the hollow section as well as the position of the same are appropriately decided to suit a user's preferences.

In the light of weight reduction of the shaft, it is preferred that the internal support structure 33 be manufactured by using a relatively light material such as a lightweight wood, expanded polystyrene, expanded polyethylene, Styrofoam, a plastic material, a fiber material, a light metal material. Moreover, this internal support structure 33 having a predetermined shape and size may be prepared in advance by machining, extrusion molding, resin injection molding or the like. When this internal support structure 33 is positioned as a support body within the hollow sections 27 (27 a and 27 b) of the shaft body 13 and the ferrule section 43, the internal support structure 33 may be set at a predetermined position within the hollow sections 27 (27 a and 27 b) by a known method such as insertion, fitting, and adhesion.

The structural members of a shaft shown in FIG. 3(2) are a cylindrical shaft body 14, a ferrule section 44 that is contiguous with the shaft body 14, and a tip section 54. The shaft body 14 is provided with a hollow section 28. Here, resin 90 is injected into the hollow section 28 to form the internal support structure 34. At this point, the resin 90 is not filled into the entire hollow section 28 to form a solid body as the internal support structure 34. Instead, a mold K1 for molding is inserted in the hollow section 28 and then the resin 90 is injected into the empty areas within the hollow section 28, so that the internal support structure 34 has the structure shown in FIG. 2-2(3 b). FIG. 3(2) explains how to manufacture the internal support structure 34 in the above manner. After injection of the resin 90 into the hollow section 28 is completed, unfilled areas along the mold K1 remain as hollows (spaces).

FIG. 3(3) is an explanatory view of the structure of a shaft having an internal support structure 35 placed in the hollow section. In the shaft having a shaft body 15 and a ferrule section 45, there is a hollow section (not shown) and the internal support structure 35 is formed or placed within the hollow section. In this case, the internal support structure 35 has the “lotus leaf” shape in cross section illustrated in FIG. 2-3(3 b) or the “rib-type” shape shown in FIG. 2-2(3 d), and spaces S10 are formed among a plurality of support bodies.

FIG. 4(1) shows a shaft body 15 having a hollow section 29 and an integrated internal support structure 60 in which an internal support structure and a ferrule section are integrated into a single piece of support structure (a ferrule-integrated structure). This drawing explains the structure of a shaft which does not have a ferrule section but has an extended connecting section. The integrated internal support structure 60 includes an internal support structure portion 60 a and the ferrule portion 60 b described above, which cannot be separated as they are combined together as a single member. Further, the internal support structure 60 may have any of the structures explained earlier with reference to FIGS. 2-1(1) to 3(c) and can be manufactured easily by machining, extrusion molding, resin injection molding and the like.

In the shaft structure shown in FIG. 4(1), the ferrule portion 60 b of the integrated internal support structure 60 is the extended connecting section. On the top end surface jt of the extended connecting section, an elastic pad 70 which matches the shape of the top end surface jt is attached with adhesive, and a tip portion 55 is further attached to the extended connecting section through the elastic pad 70.

FIG. 4(2) is an enlarged explanatory view of the shaft structure shown in FIG. 4(1). In the integrated internal support structure 60, the ferrule portion (extended connecting section) 60 b are integrated with the outer side of the internal support structure portion 60 a, and spaces S20 each having a sector shape in cross section and extending within the shaft in the longitudinal direction are arranged at five separate positions within the integrated internal support structure 60.

Hereinafter, materials of a shaft and its internal support structure of a billiard cue according to the invention are further detailed with reference to FIG. 2-1(1). In this drawing, the internal support structure 31 is positioned in the hollow section 21 provided in the shaft 110, and it is preferred that the internal support structure 31 be made so that it has better structural strength and lighter weight. In order to do so, it is preferred to use light-weight reinforced plastic, carbon fiber, stiff expanded polystyrene and the like for the internal support structure 31.

Since the shaft body 11 is usually manufactured by wood (maple) or resin, if one focuses on weight reduction in selecting a material of the internal support structure 31, it is feasible to select a material which weighs same as a normal material of the shaft body 11. Maple wood used for the shaft body 11 has an air-dried specific gravity of about 0.7, but balsa wood is lighter than maple and its air-dried specific gravity is about 0.1 to 0.2. Also, there are super light materials compared to maple wood, including expanded polystyrene (specific gravity: 0.01 to 0.02), expanded polyethylene (specific gravity: 0.01 to 0.02), and a styrene board (specific gravity: 0.1 to 0.15). However, these materials are not as stiff as wood, and therefore, when these super light materials are used, it is necessary to design the internal support structure 31 to ensure sufficient structural strength.

A material of the internal support structure 31 may be designed based on comparison of weight (specific gravity) between the internal support structure 31 and the shaft body 11, and may be selected as appropriate from light or super light wood materials, expanded polystyrene, expanded polyethylene, Styrofoam, a plastic material, a fiber material and the like. In positioning or providing the internal support structure 31 into the hollow section 21, the internal support structure 31 is manufactured so that it has the shape and size which fit into the hollow section, and the internal support structure 31 may be inserted and adhered to the hollow section. However, the internal support structure 31 may also be positioned by other ways like pushing, fitting, pressing and the like before being fixed.

Another method for manufacturing an internal support structure is to prepare mold pieces for forming hollows and use solidifying means such as resin. Specifically, these mold pieces are set at predetermined positions within the hollow section, and a liquid, a molten state resin or the like is injected into the hollow section and solidified within the hollow section to form the internal support structure. To be more specific, the internal support structure can be formed within the hollow section easily by injecting a liquid-state hardening resin such as urethane foam, epoxy resin, synthetic resin and the like.

Further, like the structure shown in FIG. 2-1(1) when manufacturing the shaft 110, the cylindrical internal support structure 31 can be manufactured in advance to match the shape and size of the hollow section 21 which runs through the inside of the shaft 110. The hollow section 21 may not be circular in cross section or may be tapered in the longitudinal direction. In that case, the internal support structure 31 needs to be designed and formed to accurately match the shape and size of such hollow section.

Regarding the procedures of joining the shaft body 11 and the ferrule section 41 of the shaft 110 and inserting the internal support structure 31 into the hollow section 21, the internal support structure 31 is first set within the hollow section 21 and then the shaft body 11 and the ferrule section 41 are joined together. However, where the ferrule section 41 has an opening on the tip section 51 side, the shaft body 11 and the ferrule section 41 may be joined together first and then the internal support structure 31 may be inserted into the hollow section 21 from the opening.

For the convenience of manufacturing, general size of the shaft 110 shown in FIGS. 2-1(1) to 2-2(5) is 737 mm in length and 12 to 13 mm in outer diameter on the top end side thereof. Therefore, the diameter of the hollow section 21 may be, for example, about 10 mm. Moreover, the shaft 110 usually tapers towards the tip section. Therefore, the longitudinal shape of the hollow section 21 may be tapered to match the shape of such shaft 110.

Although the shaft 100 usually has a circular shape in cross section, it may have polygonal or other shapes in cross section. Accordingly, the cross-sectional shape of the hollow section 21 is not limited to circle and may be formed to match the cross-sectional shape of the shaft 100.

FIGS. 5(A) to 5(H) are views illustrating various examples of the structures of a shaft of a billiard cue on the top end side. FIGS. 5(B) to 5(D) show the structures where an elastic material (elastic pad) is provided between the ferrule section 40 and the tip section 50. FIGS. 5(E) and 5(F) show structures with no ferrule section. FIG. 5(G) shows a structure where a small-size ferrule section is formed at the position where an elastic pad is usually provided. The structure shown in FIG. 5(H) is similar to that shown in FIG. 5(A) but has a pipe-like internal annulus ring section 10h which is an extension of the inner circumference part of a shaft body 10H on the side of the hollow section, formed along the inner wall of a ferrule section 40H. The interposed material such as an elastic material have functions such as absorbing impact of a ball and extending ball contact time, and may be employed as appropriate to suit player's preferences and shot feeling. Materials with high elasticity such as rubber and resin are preferred.

The structure shown in FIG. 5(A) is provided with an internal support structure 30A in the hollow section formed by a shaft body 10A and a ferrule section 40A. The ferrule section 40A has cylindrical shape with a ceiling portion A1 (bottom), and a tip section 50A (top end portion) is attached through the ceiling portion A1 of the ferrule section 40A. In other words, in this structure in FIG. 5(A), it looks like as if the ferrule section 40A with a lid covers the internal support structure 30A in the hollow section.

The structure shown in FIG. 5(B) is provided with an internal support structure 30B in the hollow section formed by a shaft body 10B and a ferrule section 40B. The ferrule section 40B has a cylindrical shape, but, unlike the structure shown in FIG. 5(A), it does not have a ceiling portion. Instead, there is an elastic pad 70B directly attached to the circular top end surface of the ferrule section 40B and the top end surface of the internal support structure 30B. Further, a tip section 50B is attached to the elastic pad 70B. In other words, FIG. 5(B) depicts a structure where the internal support structure 30B set within the shaft is covered with a pipe-like ferrule section 40B, and the elastic pad 70B is attached to the ferrule section 40B.

The structure shown in FIG. 5(C) is provided with a shaft body 10C, a ferrule section 40C, an internal support structure 30C, an elastic pad 70C, and a tip section 50C. This structure is basically the same as that shown in FIG. 5(B) but a difference is that the elastic pad 70C has an extended portion C, which is the outer edge part of the elastic pad 70C extended towards the ferrule section. Therefore, the joining area of the ferrule section 40C, where the elastic pad 70C is attached or abutted, has a shape that matches the extended portion C of the elastic pad 70C.

The structure shown in FIG. 5(D) is provided with a shaft body 10D, a ferrule section 40D, an internal support structure 30D, an elastic pad 70D, and a tip section 50D. This structure is basically the same as the structure shown in FIG. 5(B) except that the elastic pad 70D has a projected portion D1, a part of the elastic pad 70D protruding towards the internal support structure 30D. Therefore, the top surface shape of the internal support structure 30D, where the elastic pad 70D is attached or abutted, has a shape that matches the shape of the projected portion D1 of the elastic pad 70D.

The structure shown in FIG. 5(E) is provided with a shaft body 10E, an extended connecting section e1, and a tip section 50E, and, unlike the structures shown in FIGS. 5(A) to 5(D), a ferrule section is not provided. Therefore, the internal support structure 30E is a single piece (integrated) structure of a support member e2 within the hollow section and the extended connecting section e1. This internal support structure 30E is the “ferrule integrated structure,” in which a ferrule section and internal structure within a hollow section are joined together into a single piece. Since there is no ferrule section, the outer circumference of the extended connecting section e1 is exposed, which is the same as the structure explained in FIGS. 4(A) and 4(B) earlier.

The structure shown in FIG. 5(F) includes a shaft body 10F, an internal support structure 30F, an elastic pad 70E and a tip section 50F. The internal support structure 30F is a single piece (integrated) support structure including a support member f2 within the hollow section and an extended connecting section f1. Similarly to the structure shown in FIG. 5(E), this structure has no ferrule section, and the outer circumference of the extended connecting section f1 is thus exposed. The internal support structure 30F is also the “ferrule integrated structure” in which the ferrule section and the internal structure are joined together into a single piece, and is the same as the structure shown in FIG. 5(E) except that an elastic pad 70F is added. Therefore, the top area of this structure has the three-layered construction of the internal support structure 30F, the elastic pad 70F, and a tip section 50F.

The structure shown in FIG. 5(G) includes a shaft body 10G, an internal support structure 30G, a ferrule section 40G, and a tip section 50G. The internal support structure 30G is a single-piece (integrated) structure including a support member g2 within the hollow section and an extended connecting section g1, and the outer circumference of the extended connection portion g1 is exposed. The ferrule section 40G is positioned between the internal support structure 30G and the tip section 50G, and the structure of this ferrule portion 40G is slightly different from those of the other structures; the ferrule section 40G includes a circular part G1 and a ceiling part G2 and its external appearance is contiguous with the shaft body 10G and the internal support structure 30G. This structure shown in FIG. 5(G) is obtained by replacing the elastic pad 70C in the structure of FIG. 5(C) with the ferrule section 40G.

The structure shown in FIG. 5(H) is basically similar to the structure shown in FIG. 5(A), and provided with a shaft body 10H, a ferrule section 40H, and an internal support structure 30H in the hollow section formed by the shaft body 10H and the ferrule section 40H. The ferrule section 40H has a cylindrical shape with a ceiling portion H1 (bottom), and a tip section 50H (top end portion) is attached to the shaft body 10H through the ceiling portion H1. The difference from the structure of FIG. 5(A) is that this structure has a pipe-like internal annulus ring section 10 h provided in the inner side of the shaft body 10H. . The internal annulus ring section 10h is an extension of the inner circumference part of a shaft body 10H on the side of the hollow section, formed along the inner wall of a ferrule section 40H. Thus, this structure has a two-layered pipe construction in the ferrule section 41.

FIG. 6 is a view showing an example of the internal structure of a shaft of a billiard cue according to another embodiment of the present invention. FIG. 6 is an enlarged view of the top end side of the shaft 120 of a billiard cue, and the shaft 120 includes a shaft body 12, a ferrule section 41, and a tip section 52 on the end side of the ferrule section 41. A hollow section 22 is provided within the shaft 120, and an internal support structure 80 is positioned within the hollow section 22.

Here, the internal support structure 80 includes a pipe member 80A which is in close contact with the inner wall of the hollow section 22, a structure body 80B located on the side of the tip 52 within the pipe member 80A, and a solid portion 80C which fills the remaining areas within the pipe member 80A.

The pipe member 80A and the structure body 80B are similar to the internal support structure explained above (see FIGS. 2-1(1) to 4(2)). Compared with the structure shown in FIG. 2-2 (3 a), the pipe member 80A is an equivalent of the outer frame body a1, and the structure body 80B is an equivalent of the internal support member a2. The pipe member 80A and the structure body 80B are formed into a single piece by using light-weight reinforced plastic, carbon fiber, expanded polystyrene with stiffness and the like.

A material of the solid portion 80C within the pipe member 80A is light-weight wood, a plastic material, expanded polystyrene, urethane foam or the like. The material is filled, inserted, or fitted at a predetermined position in the space within the pipe member 80A except the space filled with the structure body 80B, thus the solid portion 80C is obtained.

In order to provide the internal support structure 80 in the hollow section 22 of the shaft 120, the hollow section 22 and the internal support structure 80 are manufactured so that their diameters and the longitudinal lengths match each other, and then fit each other. In that case, an adhesive may be used.

In addition, it is preferred that the hollow section 22 and the internal support structure 80 of the shaft 120 have the same length in the longitudinal direction. However, it is also possible to slightly reduce the length of the internal support structure 80 to make a space within the hollow section 22.

Alternatively, the pipe member 80A may not fill the entire space except the space filled in by the structure body 80B to create a space within the pipe member 80A.

FIG. 7(1) to 7(3) are cross-sectional views depicting examples of an internal structure of a shaft of a billiard cue according to yet another embodiment of the present invention. FIG. 7(1) shows the entire view of a shaft 160, FIG. 7(2) shows an enlarged view of the top end side of the shaft 160, and FIG. 7(3) is a view showing an example of the internal support structure, which is different from the structure shown in FIG. 7(2).

The shaft 160 in FIG. 7(1) includes a shaft body 16, a ferrule section 46, a tip section 56 provided on the end of the ferrule section 46, and a joint j6, and there is a hollow section 16C within the shaft body 16. In addition, an internal support structure 36 is placed within the hollow section 16C. The right end 36 a of the internal support structure 36 abuts on the ferrule section 46, and the length h6 between the right end 36 a and the left end 36 b represents the length of the internal support structure 36 and equal to the length of the hollow section 16C.

FIGS. 7(2) and 7(3) depict examples of the construction of the internal support structure 36 in the shaft body 16. In these drawings, the internal support structure 36 uses a support body made from a light-weight material such as a light-weight wood like balsa wood, a foam material, a carbon fiber material, and a plastic material, and this support body is filled in the hollow section 16C to support the shaft 16.

The support body made from a light-weight material as above may be formed by a single piece material or a combination or a joint body of a plurality of materials. FIG. 7(2) shows an example where the internal support structure 36 is formed from a single piece of a light-weight wood 36A such as balsa wood. FIG. 7(3) shows an example where the internal support structure 36 has a combination of a light-weight wood 36 a and a foam material 36 b.

For a shaft of a normal billiard cue, it is appropriate that the length h6 of the internal support structure 36 is about 12 to 20 cm. The entire internal support structure 36 may be formed by a single type of material as shown in FIG. 7(2) or by two types of materials that are joined together into a single piece like the structure shown in FIG. 7(3).

Further, the support body manufactured from a light-weight material and inserted into the internal support structure 36 shown in FIGS. 7(1) to 7(3) is formed so that it has shape or size that match the internal cylindrical shape of the hollow section 16C of the shaft body 16, and thus the internal support structure 36 can be manufactured extremely easily at low cost.

Furthermore, for the internal support structure 36 shown in FIGS. 7(1) to 7(3), one can freely select a combination or joining of two ore more kinds of materials, and how to combine, arrange, and mix (set a ratio) of materials can be decided freely. This means that the internal support structure 36 can be adjusted or designed to suit player's preferences and ability.

In the embodiment shown in FIGS. 7(1) to 7(3), the internal support structure 36 in the shaft body 16 is formed by a single piece or a combination of light-weight materials including light-weight wood such as balsa wood, a foam material, a carbon fiber material, a plastic material, and the like. The shaft 160 shown in FIGS. 7(1) and 7(2) has a hole (hollow section 16C) in the shaft body 16, and a light-weight wood having size and shape that fit in the hollow section 16C is inserted into the center of the hollow section 16C. As a result, the billiard cue having this shaft can give a player fulfilling feeling of billiard play without jeopardizing the natural characteristics of wood material (mainly maple) used for the shaft, including elasticity, shot feeling, and sensation. This gives the billiard cue an outstanding performance and characteristics.

The shaft structure of the present invention realizes not only weight reduction of the top end portion but also improvements in strength and stability. For example, the internal support structure 36 shown in FIG. 7(3) shows an example of a combination structure of balsa wood and a foam material, where about 70% of the structure on the back side is made from balsa wood and the remaining 30% on the top end side is made from a foam material. In this manner, the performance of the shaft can be adjusted easily to suit player's preferences and ability.

Moreover, in the shaft structure of the present invention shown in FIG. 7(3), balsa wood and a foam material maybe combined in a multiple ways to change the performance of the shaft. In addition, a path of a ball can be changed by adjusting length or thickness of a foam material. With this structure, even if a player hits a ball off-center, the more foam material is used, the more likely that the ball, though spinning, will stay on a straight path. 

1. A billiard cue formed into a single rod-like piece by a butt and a shaft that are connected to each other through a joint, wherein the shaft is provided with a hollow section running through the inside of the shaft along a center axis in a longitudinal direction, and an internal support structure is provided within the hollow section to support the hollow section from inside.
 2. The billiard cue according to claim 1, wherein the internal support structure in the hollow section is either a structure (a) including an outer frame body which abuts on an inner wall surface of the hollow section to support the same and a support member which supports the outer frame body, or a structure (b) including a support member which abuts on the inner wall surface of the hollow section and supports the same, or a structure having both of (a) and (b).
 3. The billiard cue according to claim 1, wherein the shaft is a single rod-like body made by combining a shaft body, a ferrule section, and a top end member in this order, and the hollow section is provided through inside of the shaft body and the ferrule section.
 4. The billiard cue according to claim 1, wherein the shaft is a single rod-like body made by combining a shaft body in which the hollow section is provided, an extended connecting section, and a top end member in this order, and the internal support structure is a single piece structure where a support member within the hollow section and the extended connecting section are formed into a single body.
 5. The billiard cue according to claim 1, wherein a material of the internal support structure is any of wood, urethane foam, expanded polystyrene, expanded polyethylene, Styrofoam, a plastic material, a fiber material, and a light-weight metal material.
 6. The billiard cue according to claim 2, wherein the shaft is a single rod-like body made by combining a shaft body, a ferrule section, and a top end member in this order, and the hollow section is provided through inside of the shaft body and the ferrule section.
 7. The billiard cue according to claim 2, wherein the shaft is a single rod-like body made by combining a shaft body in which the hollow section is provided, an extended connecting section, and a top end member in this order, and the internal support structure is a single piece structure where a support member within the hollow section and the extended connecting section are formed into a single body.
 8. The billiard cue according to claim 2, wherein a material of the internal support structure is any of wood, urethane foam, expanded polystyrene, expanded polyethylene, Styrofoam, a plastic material, a fiber material, and a light-weight metal material.
 9. The billiard cue according to claim 3, wherein a material of the internal support structure is any of wood, urethane foam, expanded polystyrene, expanded polyethylene, Styrofoam, a plastic material, a fiber material, and a light-weight metal material.
 10. The billiard cue according to claim 6, wherein a material of the internal support structure is any of wood, urethane foam, expanded polystyrene, expanded polyethylene, Styrofoam, a plastic material, a fiber material, and a light-weight metal material.
 11. The billiard cue according to claim 4, wherein a material of the internal support structure is any of wood, urethane foam, expanded polystyrene, expanded polyethylene, Styrofoam, a plastic material, a fiber material, and a light-weight metal material.
 12. The billiard cue according to claim 7, wherein a material of the internal support structure is any of wood, urethane foam, expanded polystyrene, expanded polyethylene, Styrofoam, a plastic material, a fiber material, and a light-weight metal material. 